Pump and motor hydraulic actuator



Feb. 16, 1954 c. J. BISHOFBERGER PUMP AND MOTOR HYDRAULIC ACTUATOR Filed Nov. 16, 1949 2 SheetsSheet l Suncntor CARL J. BISHOFBERGER Eu M attorney Feb. 16, 1954 c. .1. BISHOFBERGER PUMP AND MOTOR HYDRAULIC ACTUATOR Filed Nov. 16, 1949 2 Sheets-Sheet 2 g I SECONDARY lililfllllllllllllm 72 INIIMHIIIIIIIIII! SECONDARY TO ACTUATOR FROM PUMP lhwentor CARL J. BISHOFBERGER Gttomeg Patented Feb. 16, 1954 PUMP AND MOTOR HYDRAULIC ACTUATOR Carl J. Bishofberger, Minneapolis, Minn., assignor to. Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application November 16, 1949, Serial No. 127,749

10 Claims.

The present invention relates to hydraulic operators and more particularly to improvements in the type of hydraulic operator which. includes a pump, motor means for operating the pump and an actuator operated the pump.

It is an. object of this invention to provide in a hydraulic operator of this type a simplified design ofparts which permits economy in manufacture and ease in assembly.

It is also an. object of this invention to provide in a. hydraulic operator a sealed unit in which a single gasketmember positively seals the operator.

A further object of this invention is to provide an improved design of a motor of the transformer W1 It is another object of this invention to provide an: improved pump design for a hydraulic operator having a simplified valve mechanism.

It. is further an object of this invention to pro-- vide a simplified check valve for the pump of the hydraulic operator.

It. is still further an object of this invention to provide in an hydraulic operator of this type an improved seal for such a unit.

Another object of this invention is to provide a simplified terminal block assembly for the electric motor of the hydraulic operator, the terminal assembly isolating high and low voltage connections thereto.

These and other objects of this invention will become apparent from the reading of the attached specification together with the drawings wherein:

Figure l is a side elevation view of the operator;

Figure 2 is another side elevation view of the operator with a portion of the casing in section to show the location and arrangement of. parts;

Figure 3 is a plan view of the pump unit or the operator;

Figure 4 is an end elevation view of the pump of Figure 3;

Figure 5 is a side elevation view of the 12* mp of Figure 3 in section on the line 5'--5 of Fig. 3;

Figure 6 is a plan View of the electric motor of the operator;

Figure 7 is an end elevation view of the motor of Figure 6;

Figure 8 is a sectional View of the motor termirials; and

Figure 9 is a schematic view of the check valve.

The hydraulic operator of the subject invention, as is generally in Figures 1 and 2, is made up of a motorised pump or power unit In and the hydraulic actuator unit I l, these units being con- I5 is connected to an output lever l6 which is pivoted by means of a support member I! attached to the lower casing member 13. Vertical movement of shaft l5 causes an output link IE on the end of lever IE to similarly move up or down in the normal position of the operator, this output link being suitable for attachment to apparatus which the operator is to control, such as a damper.

Aswill be seen in Figure 2, shaft I5' is guided in its movement by means of a sleeve fitted into the aperture [8 in the lower casing member 13 and; secured thereto by suitable means such as crimping. The end of shaft I5 within the casing member i3 is attached by any suitable means (not shown) to a disk like member 2|, these members operating in a single unit which may if desired be so machined or manufactured. Disk member 2! and hence shaft l5 are urged upwardly within the lower casing member 13 by means of a compression spring 22 which encircles the sleeve 29 and shaft 15 abutting at one extremity against the lower portion of casing I3 and at the other extremity against the disk member 2|.

The disk '2! and shaft l5 form together a plunger or output portion of the hydraulic actuator whose movement in an upward direction, as previously noted, is controlled by means of spring and whose movement in a downward direction is controlled by means of a diaphragm member 23 positioned in abutting relationship with the upper surface of disk 2|. Like the casing members l2 and I3 disk member 21 and diaphragm member 2-3: are cylindrical in form. The diaphragm member is made of a suitable flexible material such as rubber and. is so positioned within the casing member l3 that it is concentric therewith and is disposed in contact with a transversely extending flange portion 24 of casing member l3. Diaphragm 23 forms the movable end wall. of a chamber which varies in volume, the chamber being completed by a supporting plate 25 also circular formed and disposed at its outer extremity on top of the diaphragm member.

Supporting plate has a dish shape configuration with three raised portions 25 spaced 129 degrees apart, the purpose of which is to form a stop member for the diaphragm and disk and provide for a given volume for chamber capacity in the collapsed position of the diaphragm member 23.

The variable chamber of the actuator unit thus formed by the diaphragm 23 and supporting plate 25 is sealed by the engagement of the diaphragm with the supporting plate, and, in addition, the diaphragm 23 is provided with a beaded or raised portion 2'! at its outer extremity which encircles the supporting plate. The supporting plate 25, diaphragm 23 and lower casing member l3 are held in assembled relationship by means of a flanged portion of the upper casing member [2 which flange forms a shoulder as at 3! against which the plate 25 abuts for the purpose of positioning the upper casing member 52 with respect to the actuator unit. Flange 35 is bent or crimped over the flange portion i l of lower casing member it, such as by spinning, to hold these parts in the above identified relationship and insure a seal between the diaphragm and support plate 25.

The flange which is channel like in cross sec tion, further urges the beaded portion 2'! of diaphragm member 23 into engagement with the end of the supporting plate and against the shoulder 3! of easing member i 2.

plate 25 and the casing member l2. While the casings l2, it, the supporting plate 25 and diaphragm 23 are best held in assembled relationship by means of bending over the flange portion 353 of easing member [2, it is to be under- .stood that any other means which clamp the casing members together may be employed.

The variable chamber formed by supporting wall 25 and diaphragm 23 is designed to receive a working fluid or medium 38 which is fed into said chamber through an aperture in the supporting wall (not shown) by means of the pump M mounted thereon by any suitable means, such as screws G2.

pressure causes the variable chamber to expand forcing the central portion of the diaphragm 23 adjacent to the disk 2| to be moved downward forcing the shaft 5 5 and disk 2| against the comsigned to provide the reservoir or sump for the working medium Ml, as indicated in Figure 2.

The pump 3!, as shown in detail in Figures 3, 4 and 5, comprises a cylindrical piston 44 positioned within the housing 45 having a cylindrical bore to fit the piston. The piston M is a solid cylindrical member having two working extremities each of which has a notch 36 or groove therein segmental in shape thereby providing at the extremities of said iston a surface which is segmental in cross section. The grooves 46, as m dicated in Figure 5, are located at opposite ends and opposite sides of the piston an and serve to cooperate with inlet ii and outlet 48 passages to the chambers formed within member 45 by piston In this manner a second seal is insured between the su porting Presence of the working medium .or fluid it in the variable chamber and under M in a manner to become evident as this disclosure proceeds.

The inlet passages 4? are located on the upper surface of the cylinder member 45 and lead to openings in the top of the pump which are covered by screens 59, the screens being retained on the member it by means of spring clips 5!. The outlet passages 38 are located in the lower portion of the pump or member 45 and similarly lead to the working chambers of the pump. As shown in Figure 3, these outlet passages 48 are connected by means of grooves 52 to the end of a check valve mechanism indicated generally at 55.

Check valve 55 which is formed within the pump structure 4i consists primarily of a hollow piston member 56 located within a second cylindrical bore 57 in member 45. This cylindrical bore 5'! of valve chamber has a pair of passages leading thereto, one passage, indicated at 58 (see Figures 4 and 9), being located in the upper surface of member 45 and venting the valve chamber to the enclosure surrounding the pump. A second passage 69 is located in the bottom of the member 45 and leads to an aperture (not shown) in the supporting plate 25 to provide a passage through the check valve mechanism to the variable chamber of the hydraulic actuator. Piston 55 within the valve chamber or bore 51 controls the opening and closing of passage 58 such that the working medium 413 may flow from the pump through the check valve mechanism to the variable chamber of the actuator when the piston is in one position and from the variable chamber through the check valve to the sump when the piston is in a second position. Piston 56 has a shoulder portion 6| formed midway along its bore, this shoulder portion cooperating with a ball check member 52 which is urged by a spring 63 to be seated on the shoulder portion and thereby forming a ball check valve member 62 within the piston. The ball check member 52 is seated on the shoulder ortion 5! by means of a spring 63 under a given spring tension in such a manner that the ball check valve formed thereby will not open until a predetermined pressure is exerted on the surface of the ball member 62. Thus, when the oil or working medium enters valve check mechanism 55 it exerts a pressure against the surface of the ball check in addition to the piston. Depending upon the pressure present in the opposite end of the piston or within the chamber 51, the piston will then move within the bore to cover the port 58 leading to the oil sump and will continue to move until a stop member 55 is engaged at which point the piston will stop. Upon increased pressure being applied to the base of the ball check member 62, this check valve will open providing a passage for the fluid through the hollow portion of the piston, that is, the ball check valve member and to the passage 50 leading to the variable chamber of the actuator unit. In the absence of pressure on the pump side 'of the check valve member, the ball check will again reseat itself and the piston will move in the opposite direction to open the passage 53 leading to the sump.

The pressure or presence of the working medium in the check valve chamber is obtained through operation of the pump whose piston 44 is designed to reciprocate within the cylindrical bores of member t5 and also oscillate in such a manner that it will alternately cover and uncover the inlet ll and outlet it passages thereto as it moves transversely within the cooperating cylinder member. The oil or working medlum 40 which enters the pump through the screened inlet port 4'! passes through the respective ends of the pump chambers depending upon which of the inlet ports are open or closed by the respective notched ends of piston 44. When the pump reciprocates and oscillates oil will be forced on through the outlet ports 48 to the check valve chamber and in the manner described above the working medium will be transmitted to the variable chamber of the actuator. The oscillating and reciprocating motion of the piston 44 is obtained by means of a ball type linkage 66 attached to the central portion of piston 44. This ball linkage or joint fits into a. bore or hole 69 eccentrically located in a drive 1 com 61 carried on the extremity of the shaft 68 of a motor 10. Rotation of the cam due to the rotation of the motor will cause the ball member attached to the piston or to describe an oscillating and reciprocating motion which motion stator 13 of the motor is made up of a plurality of laminations of magnetic material which are held together by a mounting bracket E2, the nations when assembled forming an type yoke with four poles a, 15b, 15c and d thereon.

The laminations are provided with notches such 3 that the resultant poles formed thereby have slots thereon in which are positioned shaded coils 14 on short circuited conductors. A pair of primary 16 and secondary l1 windings for stator 13 are positioned on the yoke of the stator with the two primary windings positioned on diametrically opposite sides of the yoke and the secondary windings similarly positioned as can be seen in Figure 6. Although not specifically shown, the rotor for this motor is of the conventional squirrel cage type. It is carried by the shaft 68 which is journalled in bearing members mounted also in the mounting plate 12. The primary windings 16 of this motor are designed to be connected either in a series or parallel relationship and energized from a common source to create flux lines which flow in the core structure of the motor in such a manner that they normally do not thread the rotor element and therefore cause no rotation of the motor. Secondary windings H are similarly connected in either a series or parallel relationship and, as later noted, are designed to be connected to some type of controller which will short circuit or shunt the connections to the coils. With the primary windings l6 energized and seccndary windings IT open circuited, the flux lines cre ated by the current flow in the primary windlugs 16 will circulate in a path through the yoke 73 (counterclockwise as seen in Figure 6) threading the windings I6, l7 and will not enter the poles 15a, 15b, 15c and 15d of the rotor, since the latter will provide a circuit of higher reluetance due to the air gap between the respective poles of the rotor. With the secondary or control windin s short circuited, the flux threading the secondary coils will cause a current to be generated therein which current will generate a counter flux tov effectively saturate portions of'the magnetic circuit of the motor and til ing through the shoulder 83.

force the main energizing flux lines from the primary coils I6 through the rotor element to cause a rotation of the motor rotor in a manner conventional with transformer motors. Under these conditions the flux paths for the flux lines created by the primary windings are through the portions of the yoke surrounded by the respective primary windings 76 in a counterclockwise direction, through the pole pieces 15a and 150 respectively, the rotor, the poles 75b and 15d respectively, and back through the portion of the yoke surrounded by the respective coils. The two flux paths so formed cause a clockwise rotating flux field and consequently clockwise rotation of the rotor or armature.

The primary l6 and secondary TI coils of the motor are designed to be connected to a terminal block assembly 8! located in the upper end of easing member l2 and sealed therein. Terminal assembly 81 includes a terminal block 92 having a ridge or shoulder portion 3 thereon, the terminal block 82 extending into an aperture 34 in the upper end of casing 52 and abutting against a gasket 85 encircling said aperture in said cas- A flanged member 88 attached to casing member [2 by any suit able means, such as welding, is bent over the shoulder portion 33 of the terminal assembly to secure the terminal block 82 to the casing and provide a seal at this point through gasket 85. Included within the block 82 are four terminal posts 83 to which. the extremities of the primary i5 and secondary i7 windings are connected. The upper surface of the terminal block is divided into four sections or compartments by means of a pair of transversely extending ridges or flanges t0, the terminal posts 89 terminating on the upper surface of the block in each of the com partments so formed. Primary windings 16 of the motor are connected through two of the posts 89 to a source of power by means of a cord 9! and plug 92, the wires from the cord being connected to the upper surfaces of the post by means of screws. These connections which lead to the power side (primary windings) of the motor are made at posts (also not shown) which are shorter than the posts connected to the secondary windings l! in such a manner that a cover element may be placed over the terminal block 82 to conceal such connections. The connections to the low voltage or secondary windings are made at the posts 89 which extend through the cover 95, as shown in Figure 2 and screws 93 which secure lead wires (not shown) are disposed out" side of the cover such that connections to these posts may be made from outside the terminal assembly without necessitating a removal of the cover and exposure to high voltage terminals. The cover 95 is secured to block 82 by means of a screw 91, the cover being made of an insulating material fitting tightly over the shoulder portions 83 the block to seal this portion of the operator. Similarly the connection between the block 82 and casing 12 provides a seal this point.

In operation, the operator is installed such that its output shaft 15 is extenc. A? downwardly and designed to move vertically into and out of the casing. This manner of installation insures an adequate level of oil at the pump. Primary windings iii of motor are energizedv through the cord 5H and plug 92 attached to a suitable source or" power, this energization being continuous. Upon a need for operation of the operator, the low voltage windings 11' are short 'circuited through a suitable controller (not shown) and the electric motor '10 commences rotation with the driving connection between cam l and ball linkage 66 imparting a reciprocating and oscillating motion to the piston 44 of pump 4 l. The oscillating movement of the piston member 44 operates to cover and uncover the inlet and outlet passages to the pump while reciproeating movement forces fiuid through the pump and through the outlet passages 48 into the valve check mechanism 55 of the pump. Due to the pumping action, the fluid or working medium 411 is fed under pressure to the piston 56 and ball check member 52 of the check valve mechanism causing the return or outlet passage 58 to the sump to be closed and permitting flow of fiuid through the ball or check valve mechanism through the passage 60 communicating with the variable chamber of the hydraulic actuator unit formed by the supporting plate and diaphragm member 23. The fluid or working medium 413 under pressure urges the diaphragm 23 and hence the disk 2| and shaft downwardly moving the shaft out of the confines of lower casing member l3 to cause the rotational movement of the pivoted output arm l5. Should the need for operation of the operator not be met or satisfied when the diaphragm and pivoted lever members reach their respective limits of movement, the electric motor 16 will stall under the build up in pressure load the pump and the unit will remain stalled until the secondary wind ing ll of the motor are open circuited through the respective controlling device indicating the satisfaction of the need for operation of the op erator. During this period should the pressure decrease on the pump side of the check valve mechanism, intermittent rotation of the motor and pumping action will take place to maintain the stalled pressure. Sufficient leakage past the piston of the piston member 44 pump is provided such that a decrease in pressure will be obtained on the pump side of the check valve whenever the motor is stopped. It will be understood that a small motor of this type would normally be a low torque device and consequently this leakage past the pistons of the pump also permits the motor to start rotating initially without being stalled by high pump pressure.

Upon the lack of need of operation of the operator, the electric motor is deenergized or stopped as indicated above and the leakage past the pump permits a drop in pressure on this side of the check valve. Piston 56 of the check valve member then moves under pressure from the actuator side of the pump to its inoperative position and the ball check member 62 returns to its closed position. Under such circumstances the outlet passage 58 is opened and a by-pass is formed between the variable chamber of the actuator and the sump through passages and 58 to permit the flow of the working medium back into the oil reservoir or sump. The bias of the compression spring 22 urging disk 2| and diaphragm 23 to their inoperative positions moves this fluid under pressure back to the oil reservoir. At the same time the output lever or linkage W of the operator returns to its normal position.

In considering this invention it should be kept in mind that this disclosure is intended to be illustrative only and the scope of the invention is to be determined only by the appended claims.

I claim as my invention:

1. In a device of the class described, in combination, a first sealed chamber including arr-enclosing casing member and an end'wall, a' second casing member, means including said second casing member and said end wall forming a second chamber variable in volume and attached-to said first sealed chamber, a pump mounted on saidend wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned within a pair of cooperating cylinder members each having inlet and outlet passages leading thereto, the extremities of said piston member being notched to cooperate with said inlet and outlet passages upon oscillation and reciprocation of said piston member, said piston member having a diametrical dimension slightly less than the internal diametrical di mension of said cylinder members to provide for built in leakage past said pistons, a drive mem ber mounted on said pistons intermediate its extremities, a small electric motor mounted on said pump and having limited starting torque at its output shaft for driving said pump, a coupling means connected to and driven by said output shaft of said motor and having a means ec centric of said shaft for connecting said drive member of said piston member to said coupling means to impart reciprocatory and oscillatory motion to said piston member as said motor is rotated, passage means connecting said inlet and outlet passages of said pump to said first and second chambers respectively, a third passage between said first and second chambers, means included in said third passage and controlled in one position by pressure of a fluid me dia which is pumped from said first to said second chamber upon operation of said motor and said pump for closing said third passagefthe leakage of said pump permitting operation of the same upon initial energization of said motor and operation of said means in said third passage to open said passage upon stoppage of said motor and said pump.

2. In a device of the class described, in combination, a first sealed chamber including an enclosing casing member and an end wall, a second casing member, means including said second casing member and said end wall forming a second chamber variable in volume and attached to said first sealed chamber, a pump mounted on said end wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned within a pair of cooperating cylinder members each having inlet and outlet passages leading thereto, the extremities of said piston member being so formed that they are segmental in cross-section to thereby cooperate with the inlet and outlet passages of said cylinder upon oscillation and reciprocation of said piston member, said piston member and said cylinder so cooperating to provide for a predetermined amount oi leakage past said piston member, a small electric motor mounted on said pump and having limited starting torque for driving said pump, an eccentric coupling means connecting said motor and said piston member and driven by said motor to impart reciprocatory and oscillatory movements to said piston member as said motor is rotated, means connect ing said inlet and outlet passages of said pump to said first and second named chambers respectively, a third passage between said first and second chambers bypassing said pump, means included in said third passageway and'jcontr'o'lled 9 in one position by pressure of a fluid medium which is pumped from said first to said second chambers upon operation of said motor and said pump for closing said third passageway, the leakage of said pump permitting operation of the same upon initial. energization of the motor.

3. In a device of the class described, a first sealed chamber including an enclosing casing member end wall, a motorized pump within said chamber and mounted on said end wall, a second casing member, means including said second casing member and said end wall forming a second chamber variable in volume and attached to said first sealed chamber, a working medium within said first chamber, means including said pump havin built in leakage for moving said working medium from said first chamber to said second chamber upon the happening of a predetermined condition, means for moving said working medium from said second chamber to said first chamber in the absence of said predetermined condition, said second named means including valve means with a hollow piston member slidably positioned in a cooperating cylir having inlet and outlet ports therein, a check valve positioned within said hollow member, said piston being movable within said cyiinder upon the presence of a predetermined pressure at the pump to close outlet port and permit passage of said working medium through said ball check valve and said inlet port into said variablechamber and to open said outlet port in the absence of said predetermined pressure the pump, and means responsive to the presence of said working medium in said second chamber.

4. In a device of the class described, a first sealed chamber including an enclosing casing member and an end wall, a motorized pump within said sealed chamber and mounted on said end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, one of said casing members including a shoulder portion which is bent over an edge of said end wall, an edge of said diaphragm and a shoulder portion on said other casing member to maintain said device in assembled relationship, and a beaded flange portion on the edge of said diaphragm abutting the peripheral side and end surfaces of the edge of said end wall and abutting both of said casing members to provide a seal for both said first and said second chambers.

5. In a device of the class described, a first sealed chamber including an enclosing casing member and an end wall, a motorized pump within said chamber and mounted on said end wall, a second sealed chamber formed by a fiexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, means including said first and second casing members for maintaining said device in assembled relationship, a flange portion on said diaphragm abutting casing members and said end wall to form a seal for said first and second chambers, a working medium Within said first chamber, means including said pump having a built inleakage for moving said working medium from said first chamber to said second chamber upon the happening of a predetermined condition, means for moving said working medium from said second chamber to said first chamber in the absence of said predetermined condition, said second named means including valve means with a hollow piston member slidably positioned in a cooperating cylinder having inlet and outlet ports therein, a ball check valve positioned within said hollow piston member, said piston being movable within said cylinder upon the presence of a predator pressure at the pump to close said outlet port and permit passage of said working medium through said ball check valve and said inlet port into said variable chamber and to open said outlet port in the absence of said predetermined pressure at the pump, and means responsive to the presence of said working medium in said second chamber.

6. In a device of the class described, in combination, a first sealed chamber including an enclosingcasing member and an end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, means including said first and second casing in acre for maintaining said device in assembled relationship, a flange portion on said diaphragm abutting said casing members and said end wall to form a seal between said first and second chambers, a pump mounted on said end wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned. within a pair of cooperating cylinder members each having inlet and cutiet passages leading thereto, the extremities of said piston member being notched to cooperate with said inlet and outlet passages upon oscillation and reciprocation of said piston member, said piston member having a diainetrical dimension slightly less than the internal diametrical dimension of said cylinder members to provide for built in leakage past said pistons, a drive member mounted. on said pistons intermediate its extremities, a small electric motor mounted on said pump and having limited starting torque at its output shaft for driving said pump, a coupling means connected to and driven by said output shaft of said motor and having a means eccentric of said. shaft for comiecting said drive member of said piston member to said coupling means to impart reciprocatory and oscillatory motion to said piston member as said motor is rotated, passage means connecting said inlet and outlet passages of said pump to said first and second chambers respectively, a third passage between said first and second chambers, means included in said third passage and controlled in one position by pressure of a fluid media which is pumped from said first to said second chamber upon operation of said motor and said pump for closing said third passage, the leakage of said pump permitting operation of the same upon initial energization of said motor and operation of said means in said third passage to open said passage upon stoppage of said motor and said pump.

7. In a device of the class described, in combination, a first sealed chamber including an enclosing casing member and an end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, means including said first and second casing members for maintaining said device in assembled relationship, a flange portion on said diaphragm abutting said casing members and said end wall to form a seal between said first and second chambers, a pump mounted on said end wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned within a pair of cooperating cylinder members each having inlet and outlet passages leading thereto, the extremities of said piston member being so formed that they are segmental in crosssection to thereby cooperate with the inlet and outlet passages of said cylinder upon oscillation and reciprocation of said piston member, said piston member and said cylinder so cooperating to provide for a predetermined amount of leakage past said piston member, a small electric motor mounted on said pump and having limited starting torque for driving said pump, an eccentric coupling means connecting said motor and said piston member and driven by said motor to impart reciprocatory and oscillatory movements to said piston member as said motor is rotated, means connecting said inlet and outlet passages of said pump to said first and second named chambers respectively, a third passage between said first and second chambers bypassing said pump, means included in said third passageway and controlled in one position by pressure of a fluid medium which is pumped from said first to said second chambers upon operation of said motor and said pump for closing said third passageway, the leakage of said pump permitting operation of the same upon initial energization of the motor.

8. In a device of the class described, in combination, a first sealed chamber including an enclosing casing member and an end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, means including said first and second casing members for maintaining said device in assembled relationship, means including said first and second casing members and a peripheral edge of said diaphragm for maintaining said device in assembled relationship and sealing said second chamber, a pump mounted on said end wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned within a pair of cooperating cylinder members each having inlet and outlet passages leading thereto, the extremities of said piston member being notched to cooperate with said inlet and outlet passages upon oscillation and reciprocation of said piston member, said piston member having a diametrical dimension slightly less than the internal diametrical dimension of said cylinder members to provide for built in leakage past said pistons, a drive member mounted on said pistons intermediate its extremities, a small electric motor mounted on said pump and having limited starting torque at its output shaft for driving said pump, a coupling means connected toand driven by said output shaft of said motor and having a means eccentric of said shaft for connecting said drive member of said piston member to said coupling means to impart reciprocatory and oscillatory motion to said piston member as said motor is rotated, passage means connecting said inlet and outlet passages of said pump to said first and second chambers respectively, a third passage between said first and second chambers, means included in said third passage and controlled in one position by pressure of a fluid media which is pumped from said firstv to said second chamber upon operation of said motor and said pump for closing said third passage, the leakage of said pump permitting 12 operation of the same upon initial energization of said motor and operation of said means in said third passage to open said passage upon stoppage of said motor and said pump.

9. In a device of the class described, in combination, a first sealed chamber including an enclosing casing member and an end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing meme ber enclosing said second sealed chamber, means including said first and second casing members for maintaining said device in assembled relationship, means including said first and second casing members and a peripheral edge of said diaphragm for maintaining said device in assembled relationship and sealing said second chamber, a pump mounted on said end Wall and located within said first sealed chamber, said pump including a double ended reciprocating and oscillating piston member slidably positioned within a pair of cooperating cylinder members each having inlet and outlet passages leading thereto, the extremities of said piston member being so formed that they are segmental in crosssection to thereby cooperate with the inlet and outlet passages of said cylinder upon oscillation and reciprocation of said piston member, said piston member and said cylinder so cooperating to provide for a predetermined amount of leakage past said piston member, a small electric motor mounted on said pump and having limited starting torque for driving said pump, an eccentric coupling means connecting said motor and said piston member and driven by said motor to impart reciprocatory and oscillatory move ments to said piston member as said motor is rotated, means connecting said inlet and outlet passages of said pump to said first and second named chambers respectively, a third passage between said first and second chambers bypassing said pump, means included in said third passageway and controlled in one position by pressure of a fluid medium which is pumped from said first to said second chambers upon operation of said motor and said pump for closing said third passageway, the leakage of said pump permitting operation of the same upon initial energization of the motor.

10. In a device of the class described, a first sealed chamber including an enclosing casing member and an end wall, a motorized pump within said chamber and mounted on said end wall, a second sealed chamber formed by a flexible diaphragm and said end wall, a second casing member enclosing said second sealed chamber, means including said first and second casing members for maintaining said device in assembled relationship, means including said first and second casing members and a peripheral edge of said diaphragm for maintaining said device in assembled relationship and sealing said second chamber, a working medium within said first chamber, means including said pump having a built in leakage for moving said working medium from said first chamber to said second chamber upon the happening of a predetermined condi tion, means for moving said working medium from said second chamber to said first chamber in the absence of said predetermined condition, said second named means including valve means with a hollow piston member slidably positioned in a cooperating cylinder having inlet and outlet ports therein, a ball check valve positioned within said hollow piston member, said piston being movable within said cylinder upon the presence 13 of a. predetermined pressure at the pump to close said outlet port and permit passage of said working medium through said ball check valve and said inlet port into said variable chamber and to open said outlet port in the absence of said 5 predetermined pressure at the pump, and means responsive to the presence of said working medium in said second chamber.

CARL J. BISHOFBERGER.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Number Name Date Wile Nov. 17, 1936 Seitner Nov. 2, 1937 Larocca Nov. 30, 1937 Ray Aug. 23, 1938 Ray Mar. 17, 1942 Baak Aug. 4, 1942 Ray Apr. 30, 1946 Whitted Apr. 8, 1952 FOREIGN PATENTS Country Date Great Britain Sept. 21, 1939 

